Solar water splitting over Rh_0.5Cr_1.5O₃-loaded AgTaO₃ of a valence-band-controlled metal oxide photocatalyst

Improvement of water splitting performance of AgTaO₃ (BG 3.4 eV) of a valence-band-controlled photocatalyst was examined. Survey of cocatalysts revealed that a Rh_0.5Cr_1.5O₃ cocatalyst was much more effective than Cr₂O₃, RuO₂, NiO and Pt for water splitting into H₂ and O₂ in a stoichiometric amount. The optimum loading amount of the Rh_0.5Cr_1.5O₃ cocatalyst was 0.2 wt%. The apparent quantum yield (AQY) at 340 nm of the optimized Rh_0.5Cr_1.5O₃(0.2 wt%)/AgTaO₃ photocatalyst reached to about 40%. Rh_0.5Cr_1.5O₃(0.2 wt%)/AgTaO₃ gave a solar to hydrogen conversion efficiency (STH) of 0.13% for photocatalytic water splitting under simulated sunlight irradiation. Bubbles of gasses evolved by the solar water splitting were visually observed under atmospheric pressure at room temperature.